B2: Organisation Flashcards
What is a tissue?
Groups of cells that have similar structures and functions
What is an organ?
A group of tissues working together to perform a specific function
What is an organ system?
Groups of organs working together
What is the order of the digestive system and each part’s function?
- Teeth; break down food mechanically; saliva contains amylase
- Oesophagus; food travels down
- Stomach; contains hydrochloric acid & enzymes that chemically break down food
- Liver; produces bile, stored in gall bladder before going into small intestine
- Pancreas; secretes amylase which breaks down starch into glucose in the small intestine
What is the function of bile?
- Neutralise stomach acid
- Emulsify lipids to form droplets, increasing their surface area
How are nutrients absorbed into the bloodstream?
Via villi in the small intestine
How is water absorbed into the bloodstream?
Via the large intestine
What are enzymes?
Biological catalysts
Proteins
Often break down molecules into shorter ones
What does amylase break down and what is the product?
Breaks down starch into glucose
What does protease break down and what is the product?
Breaks down proteins into amino acids
What does lipase break down and what is the product?
Breaks down fats into fatty acids and glycerol
How do enzymes work (lock and key theory)?
- The enzyme’s active site is a specific shape
- The enzyme will only catalyse a specific reaction because the substrate fits into its active site
- At the active site, enzymes can break molecules down into smaller ones or bind small molecules together to form larger ones
- When the products have been released, the enzyme’s active site can accept another substrate molecule
How does temperature affect enzyme activity?
Activity increases with temperature until the optimum temperature is reached and then the enzyme starts to denatures when it gets too hot
What happens when an enzyme denatures?
The active site changes shape
How does pH affect enzyme activity?
Activity increases until optimum pH and then decreases
What is the enzyme practical for starch?
- Mix amylase with starch and start timer
- Remove a few drops from mixture every 10 seconds and add to iodine
- Record the time taken for no starch to be detected (will remain orange)
- Repeat at different temperatures or with different pH buffer solutions added
- Optimum pH/temp is between two lowest times
What is the food test for starch?
Turns iodine from orange to black when starch is present
What is the food test for sugars?
Turns 10 drops Benedict’s solution from blue to orange when sugar is present
Must be heated in a water bath of 95 degrees celcius for five minutes
On a scale - green = small amount of sugar, brick red = large amount of sugar
Only works with reducing sugars such as glucose
What is the food test for protein?
2cm^3 food solution and 2cm^3 biuret solution
Turns biuret’s reagent from blue to purple when protein is present
What is the food test for lipids (fats)?
Grind food with distilled water using mortar and pestle but do not filter
Add few drops of distilled water and ethanol
Gently shake solution
Turns cold ethanol cloudy when lipids (fats) are present
Where does air travel through the respiratory system?
- Trachea
- Bronchi
- Bronchioles
- Alveoli
What are features of the alveoli to maximise gas exchange?
- Large surface area
- Lots of capillaries (good blood supply)
- Moist
- Thin walls
How does oxygen diffuse into the bloodstream?
- Diffuses into bloodstream through alveoli
- Binds to the haemoglobin in red blood cells to be transported
What is dissolved into the plasma of the blood and then exhaled?
Carbon dioxide
What is a double circulatory system?
Blood enters the heart twice every time it is pumped round the body
Where does deoxygenated blood enter?
The right side through the vena cava
What are valves in the heart used for?
To prevent backflow
Where does blood go after the vena cava?
Right atrium
Where does blood go after the right atrium?
Right ventricle
Where does deoxygenated blood exit the heart?
The right side through the pulmonary vein
Where does blood go after exiting the pulmonary vein?
To the lungs to be oxygenated
Where does oxygenated blood enter?
The left side through the pulmonary vein
Where does blood go after the pulmonary vein?
Left atrium